I took the index with the words, converted the quantity to binary, extra a few zeros, calculated the sha256 digest, took the 1st part of the hexadecimal to convert it to binary, extra three zeros to your 8 digits in the binary and acquired 00000010011 which translates to 19 in https://allkindsofsocial.com/story4148533/bip39-phrase-generator-can-be-fun-for-anyone